The Blazers say the former No. 1 pick in the 2007 NBA draft was to have the surgery Monday in Vail, Colo.

The often-injured 7-footer had the same surgery on his right knee earlier this month.

*UPDATE*

Oden was suppose to just get a scope, but turned into a microfracture surgery.

“Initially, Greg was undergoing a procedure similar to the one he had a couple of weeks ago to have debris cleared from his right knee,” said Acting General Manager Chad Buchanan . “However, once the doctors were inside Greg’s left knee, they unfortunately found articular surface damage and determined microfracture was necessary.”